A better understanding of the mechanism which converts chemical energy (from ATP) into work in the mammalian sperm is the objective of the proposed investigation. Exploration and characterization of the ATPase activity of motile sperm will be done by using a procedure which allows the monitoring of ATPase activity and motility at the same time. Chemical agents which are known to alter sperm motility (e.g., cAMP, Ni ions, ADP, Mg ions) will be tested for their effect on the rate of ATP hydrolysis and the efficiency of the transduction of energy from ATP into movement. The site of action of chemical agents which change sperm motility will also be examined. Experiments designed to localize the regions of the sperm structure which are effected by such agents will be carried out; and an attempt will be made to discover the nature of the chemical interaction between each effector substance and the involved sperm components. A novel technique which allows fully motile sperm to be studied with and without an intact plasma membrane will be used to analyze the role of both the external and internal environments of the cell as well as the role of the plasma membrane in motility. The results of this investigation are expected to enhance our knowledge of the integration of the chemical and mechanical processes which underlie motility in mammalian sperm, and could ultimately provide a basis for the regulation of conception through alterations of sperm motility.